Atwood Water Heater: “ECO open / tripped”
warning RV water heater fault codes
What it means
The ECO is a backup high-limit temperature switch wired in series with the control. On DSI/electronic models it is a surface-mounted disc thermostat that, with the regular thermostat, controls current to the circuit board; if it opens, the board loses its enabling circuit and the unit will not fire (showing as a lock-out / fault lamp). On gas/pilot operation the ECO in the gas valve trips permanently open if water temperature exceeds about 190 F; on the 110V electric backup thermostat/ECO the backup trips if water exceeds about 170 F. There is also a manual-reset high-temperature limit switch on the 110V electric side.
Most likely causes
- Genuine over-temperature event (e.g., thermostat stuck closed letting water overheat) common
- ECO disc not seated flush against the tank or a defective/open ECO common
- Loose or corroded wiring at the ECO terminals common
- On 110V electric side, the manual-reset high-temp limit switch has tripped and needs its reset button pressed less common
Safe checks you can do yourself
- On the 110V electric portion, with power OFF, locate and press the manual-reset (ECO re-set) button on the high-temperature limit switch.
- With power off and a multimeter, check continuity across the ECO; an open ECO with cold water means it is blown and must be replaced.
- Confirm the ECO and thermostat discs are seated flush against the tank surface.
- Inspect and tighten the ECO terminal wiring for corrosion or looseness.
How to reset / clear ECO open / tripped
- For the 110V electric backup, press the manual reset button after the water has cooled.
- The gas-side ECO in the valve trips permanently open and is not resettable; if blown it must be replaced.
- Restore power / switch the heater off and on once the limit device is reset or replaced.
When to call a technician
If the ECO keeps tripping after reset/replacement, or the thermostat is suspected of running the water too hot, stop and call a qualified RV technician.
Applies to
G6A-8E · GC6AA-10E · GCH6A-10E · GC10A-4E · GCH10A-4E · GC6AA-7E
FAQ
What does Atwood Water Heater code "ECO open / tripped" mean?
The ECO is a backup high-limit temperature switch wired in series with the control. On DSI/electronic models it is a surface-mounted disc thermostat that, with the regular thermostat, controls current to the circuit board; if it opens, the board loses its enabling circuit and the unit will not fire (showing as a lock-out / fault lamp). On gas/pilot operation the ECO in the gas valve trips permanently open if water temperature exceeds about 190 F; on the 110V electric backup thermostat/ECO the backup trips if water exceeds about 170 F. There is also a manual-reset high-temperature limit switch on the 110V electric side.
How do I reset Atwood Water Heater ECO open / tripped?
For the 110V electric backup, press the manual reset button after the water has cooled. The gas-side ECO in the valve trips permanently open and is not resettable; if blown it must be replaced. Restore power / switch the heater off and on once the limit device is reset or replaced.
What is the most common cause of ECO open / tripped on a Atwood Water Heater?
The most likely cause is genuine over-temperature event (e.g., thermostat stuck closed letting water overheat).
Related · Atwood water heater
On Atwood DSI (Direct Spark Ignition) water heaters there is… Gas & spark, no flame proven
A diagnostic sub-condition of the DSI lock-out: both gas and… Gas present, no spark
A diagnostic sub-condition of the DSI lock-out from the offi… No spark / no ignition
Dead unit with no spark at the electrode and no lockout-ligh… Spark present, no gas
A diagnostic sub-condition of the DSI lock-out from the offi… TCO (thermal cut-off) tripped
Current Atwood DSI water heaters have a one-shot thermal cut…
Sources
- Atwood Water Heaters Service Manual (DSI Sequence of Operation; 110VAC Bolt-In / Screw-In Heating Element, Thermostat & ECO Trouble-Shooting) — Pilot Sequence E.C.O. trips above 190F; Screw-In Element ECO backup trips above 170F; manual-reset high-temp limit switch on 110V side (Atwood Mobile Products LLC)
Note: Trip temperatures (190 F gas-side ECO, 170 F electric backup, 190 F one-shot thermal cut-off) are from the Atwood manual and vary by model/era; the gas-side ECO is non-resettable while the 110V high-limit has a manual reset button. Always confirm against the label on the specific unit.
● Last verified 2026-06-29 · compiled from manufacturer documentation. Codes can vary by model year — always cross-check your unit’s manual.